/** loading css */
.dot {
    position: relative; /*absolute*/
    display:inline-block; /*使div共处同一行*/
    width: 5px;
    height: 5px;
    border-radius: 20px;
    top: 50%;
    background-color: #007bff; /*#0097FB*/
    -webkit-transform: translate(0, -50%);
            transform: translate(0, -50%);
    -webkit-animation: 3s linear loader infinite;
            animation: 3s linear loader infinite;
  }
  
  .dot:nth-of-type(1) {
    left: 0px;
  }
  
  .dot:nth-of-type(2) {
    left: -10px;
    -webkit-animation-delay: 0.15s;
            animation-delay: 0.15s;
  }
  
  .dot:nth-of-type(3) {
    left: -20px;
    -webkit-animation-delay: 0.3s;
            animation-delay: 0.3s;
  }
  
  .dot:nth-of-type(4) {
    left: -30px;
    -webkit-animation-delay: 0.45s;
            animation-delay: 0.45s;
  }
  
  .dot:nth-of-type(5) {
    left: -40px;
    -webkit-animation-delay: 0.60s;
            animation-delay: 0.60s;
  }
  
  @-webkit-keyframes loader {
    0%, 20% {
      -webkit-transform: translate(0, -50%);
              transform: translate(0, -50%);
      opacity: 0;
    }
    35% {
      -webkit-transform: translate(45vw, -50%);
              transform: translate(45vw, -50%);
      opacity: 1;
    }
    65% {
      -webkit-transform: translate(55vw, -50%);
              transform: translate(55vw, -50%);
      opacity: 1;
    }
    80%, 100% {
      -webkit-transform: translate(100vw, -50%);
              transform: translate(100vw, -50%);
      opacity: 0;
    }
  }
  
  @keyframes loader {
    0%, 20% {
      -webkit-transform: translate(0, -50%);
              transform: translate(0, -50%);
      opacity: 0;
    }
    35% {
      -webkit-transform: translate(45vw, -50%);
              transform: translate(45vw, -50%);
      opacity: 1;
    }
    65% {
      -webkit-transform: translate(55vw, -50%);
              transform: translate(55vw, -50%);
      opacity: 1;
    }
    80%, 100% {
      -webkit-transform: translate(100vw, -50%);
              transform: translate(100vw, -50%);
      opacity: 0;
    }
  }